Production of Sei Whale (Balaenoptera borealis) Cloned Embryos by Inter- and Intra-Species Somatic Cell Nuclear Transfer

Abstract

Abstract. The objectives of this study were to choose an effective embryo reconstruction method and an effective postactivation agent for in vitro production of sei whale (Balaenoptera borealis) interspecies somatic cell nuclear transfer (iSCNT) embryos. Moreover, trichostatin A (TSA) treatment of whale iSCNT embryos was performed to improve the in vitro embryo development. In Experiment 1, the fusion rate was significantly higher (88.1%) in embryos reconstructed using the intracytoplasmic cell injection method (ICI) than that (48.7%) in the subzonal cell insertion (SUZI) counterpart. The rates of pseudopronucleus (PPN) formation (77.4 vs. 77.2%) and cleavage (24.5 vs. 37.0%) did not vary between ICI and SUZI. However, the PPN formation and cleavage rates were significantly (P<0.05) lower in the iSCNT embryos than in the parthenogenetic control (95.7% and 64.4%, respectively). Although 21.5% of the bovine parthenogenetic embryos developed to the blastocyst stage, no iSCNT embryo developed beyond the 6-cell stage. In Experiment 2, the cleavage rate did not vary between the TSA (50 nM)-treated and non-treated whale iSCNT embryos (30.5 vs. 32.3%, respectively). Moreover, it did not vary between the TSA-treated iSCNT and SCNT embryos (30.5 vs. 32.0%, respectively). Only one TSA non-treated iSCNT embryo developed to a compacted morula with 20 nuclei. One TSAtreated whale SCNT embryo developed to the 8-cell stage, and out of five whale iSCNT embryos, a 6-cell stage embryo was positive for whale DNA. In conclusion, bovine oocytes have the ability to support development of sei whale nuclei up to the 6-cell stage. Key words: Interspecies, Somatic cell nuclear transfer, Whale (J. Reprod. Dev. 56: [131][132][133][134][135][136][137][138][139] 2010) esearch on in vitro maturation (IVM), in vitro fertilization (IVF), somatic cell nuclear transfer (SCNT) and in vitro culture (IVC) of whale embryos will greatly contribute to our basic understanding of whale reproductive physiology, resulting, ideally, in the application of various assisted reproductive technologies (ARTs) to increase the population and aid in management of cetaceans. Several studies on ARTs with respect to IVM [1][2][3][4][5][6], cryopreservation of oocytes [2,5,7], IVF [3,8], intracytoplasmic sperm injection (ICSI) [5,6,9] and interspecies SCNT [10] have been conducted in Common minke (Balaenoptera acutorostrata) and Antarctic minke (B. bonaerensis) whales. Recently, we attempted for the first time to produce embryos of sei (B. borealis) whales by IVF of IVM oocytes in a research based ship [11]. However, there is no information available concerning the production of SCNT embryos in sei whales. The authors had the opportunity to board a vessel in the North Pacific Ocean in 2007 to collect a sei whale fetus and to establish a fetal fibroblast cell line for an attempt to produce whale cloned embryos by SCNT. It has been demonstrated elsewhere that bovine, porcine and rabbit oocytes can support remodeling and reprogramming of somatic cells from different sp...

Histone Deacetylase Inhibitor Improves the Development and Acetylation Levels of Cat–Cow Interspecies Cloned Embryos

“…Therefore, reduction of the development of iSCNT cat embryos may result in part from the exposure of TSA with a high concentration. In contrast to our results, TSA treatment has been shown to have no effects on the embryonic development of iSCNT, e.g., guar-cow (Srirattana et al, 2012), human-rabbit (Shi et al, 2008), and sei whalecow (Bhuiyan et al, 2010). The difference in results might be associated with the TSA applications (concentration, timing, and the onset of treatment), species-specific effects, and phylogenetic distance between the oocyte and somatic cell donor.…”

Irregular transcriptome reprogramming probably causes thec developmental failure of embryos produced by interspecies somatic cell nuclear transfer between the Przewalski’s gazelle and the bovine

“…Interspecies SCNT (iSCNT) where endangered animal somatic cell nuclei are transferred to domestic oocyte cytoplasts is an approach that might minimize the limitations of SCNT. Many trials of iSCNT have been reported in wildlife species such as the giant panda ( Ailuropoda melanoleuca ) [ 6 , 7 ], Tibetan antelope ( Pantholops hodgsonii ) [ 8 ], Banteng ( Bos javanicus ) [ 9 ], yak ( Bos grunniens ) [ 10 ], Siberian tiger ( Panthera tigris altaica ) [ 11 ], and Sei whale ( Balaenoptera borealis ) [ 12 ]. The iSCNT cloned embryos generated in these studies had extremely poor development to the blastocyst stage.…”

Recent progress in reproduction of whale oocytes

“…Both intracytoplasmic cell injection (ICI) and subzonal cell insertion (SUZI) are equally effective with respect to PPN formation and cleavage of sei whale iSCNT embryos. Bovine oocytes have the ability to support development of sei whale nuclei up to the 6-cell stage (Bhuiyan et al ., 2010). Sei whale iSCNT embryos can also be reconstructed using porcine oocytes.…”

“…The high rates of developmental blockage in whale iSCNT might be due to failure in timely activation of the whale embryonic genome. Further studies are needed on reprogramming mechanism of whale nuclei at the molecular level to gain a better understanding of development in iSCNT embryos (Bhuiyan et al ., 2010). Thus, development of iSCNT embryos may provide some information about whale embryo development.…”